The present invention has for its object a process for continuous sterilization of liquid or pasty products. The choice of the use of a tubular exchanger for practicing the process results from the fact that one of the objects of the invention is to provide a process for sterilization by indirect heating which is much more respectful of the product to be treated than the process for sterilization by direct heating used at present or of superheated steam being injected to the product to be treated to raise its temperature. Carrying out direct steam injection is difficult to perform under good conditions, particularly when the temperature must reach values higher than 150xc2x0 C. to eliminate highly resistant spores and above all gives rise to a modification of the composition of the product by adding water to it, which must then be eliminated from the treated product.
The first object of the invention is thus to provide a process for the sterilization by indirect heating which can eliminate highly resistant spores, which is to say to raise the temperature of the product to be treated to at least 150xc2x0 C.
A second object of the invention is to provide a process for sterilization which respects the qualities of the treated product, which is particularly important when the product to be treated is a liquid foodstuff, milk, fruit juice, etc . . . or a liquid used in cosmetics for the production of pharmaceutical products. It is particularly important that the sterilization, whilst eliminating bacteria and highly resistant spores does not modify the taste, the colors, the composition or other characteristics of the products to be treated. It is at least an object of the present invention to provide a process for sterilization which better respects the products to be treated than the existing processes by direct heating.
Still another object of the present invention is to provide a process for sterilization which causes little or no fouling of the tubes for passage of the product to be treated, so as to be able to operate a sterilization installation for at least 16 hours without shutting down and hence without clinging, so as to obtain higher profitability than the existing products for sterilization which permit continuous operation only for several hours, at the most seven to eight hours.
The present invention has for its object a process for continuous sterilization that overcomes the drawbacks of the known processes and permits indirect heating of the product to be treated, a greater respect for the qualities and characteristics of the product to be treated and which can be used without shutdown for a duration of more than 16 hours. This continuous sterilization process is distinguished by the characteristics set forth in claim 1.